Toner compositions
AssigneeXerox Corporation
InventorsBeng S. Ong, Walter Mychajlowskij, Raj D. Patel
Life of this patent
Estimating the term…
Abstract
A toner comprised of color pigment and an addition polymer resin, and wherein said resin is generated by emulsion polymerization of from 70 to 85 weight percent of styrene, from about 5 to about 20 weight percent of isoprene, from about 1 to about 15 weight percent of acrylate, or from about 1 to about 15 weight percent of methacrylate, and from about 0.5 to about 5 weight percent of acrylic acid.
Claims34
A dry toner consisting essentially of pigment and an addition polymer resin, and wherein said resin is generated by emulsion polymerization of from about 70 to about 85 weight percent of styrene, from about 5 to about 20 weight percent of isoprene, from about 1 to about 15 weight percent of acrylate, or from about 1 to about 15 weight percent of methacrylate, and from about 0.5 to about 5 weight percent of acrylic acid, and wherein said emulsion polymerization consists essentially of shearing a pigment dispersion with a latent emulsion containing said addition polymer resin, heating the resulting mixture below about the glass transition temperature of said addition polymer resin, and thereafter, heating above about addition polymer resin glass transition temperature, and optionally separating and drying said toner.
A dry toner consisting essentially of pigment and a styrene-isoprene-acrylate-acrylic acid resin or styrene-isoprene-methacrylate-acrylic acid resin, and wherein said resin is generated by the emulsion polymerization of from about 75 to about 85 weight percent of styrene, about 5 to about 15 weight percent of isoprene, about 1 to about 15 weight percent of acrylate or about 1 to about 15 weight percent of methacrylate, and about 0.5 to about 3 weight percent of acrylic acid, and wherein said resin possesses a weight average molecular weight (M.sub.w) of from about 20,000 to about 35,000 and a number average molecular weight (M.sub.n) of from about 6,000 to about 10,000 relative to a styrene standard, and wherein said emulsion polymerization consists essentially of shearing a pigment dispersion with a latex emulsion containing an ionic surfactant having an opposite charge polarity to that of said ionic surfactant in the pigment dispersion wherein the pigment dispersion consists essentially of a pigment and an ionic surfactant, and wherein said addition polymer resin in the emulsion contains from about 75 to about 85 weight percent of styrene, about 5 to about 15 weight percent of isoprene, about 1 to about 15 weight percent of acrylate, or about 1 to about 15 weight percent of methacrylate, and about 0.5 to about 3 weight percent of acrylic acid, and wherein said resin possesses a weight average molecular weight (M.sub.w) of from about 20,000 to about 35,000and a number average molecular weight (M.sub.n) of from about 6,000 to about 10,000, relative to a styrene standard, and said resin is stabilized with an optional nonionic surfactant causing a flocculation of the resin, pigment, and surfactants;
- by heating with stirring at a temperature of from about 25.degree. C. below to about 1.degree. C. below the glass transition temperature (Tg) of the resin to effect formation of toner sized aggregates, and wherein the resin has a Tg of from about 45.degree. C. to about 65.degree. C.;
- heating the aggregates from about 10.degree. C. to about 55.degree. C. above the Tg of the resin to form toner particles comprised of said polymeric resin, pigment and optionally a charge control agent;
- and optionally separating and drying said toner.
A process for the preparation of dry toner compositions consisting essentially of:
- (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant and optionally a charge control agent;
- (ii) shearing the pigment dispersion with a latex emulsion derived from a mixture of styrene, isoprene, acrylate or methacrylate, and acrylic acid, and wherein said resin is generated by the emulsion polymerization of from about 75 to about 85 weight percent of styrene, about 5 to about 15 weight percent of isoprene, about 1 to about 15 weight percent of acrylate or about 1 to about 15 weight percent of methacrylate, and about 0.5 to about 3 weight percent of acrylic acid, and wherein said resin possesses a weight average molecular weight (M.sub.w) of from about 20,000 to about 35,000 and a number average molecular weight (M.sub.n) of from about 6,000 to about 10,000 relative to a styrene standard, and said resin is stabilized with an optional nonionic surfactant and an ionic surfactant having an opposite charge polarity to that of said ionic surfactant in the pigment dispersion, thereby causing a flocculation of the resin, pigment, surfactants, and optional charge control additive particles;
- (iii) heating the above flocculent mixture with stirring at a temperature of from about 25.degree. C. below to about 1.degree. C. below the glass transition temperature (Tg) of the resin to effect formation of electrostatically bounded toner sized aggregates with a narrow aggregate size distribution, and wherein the resin has a Tg of from about 45.degree. C. to about 65.degree. C.;
- (iv) heating the aggregates from about 10.degree. C. to about 55.degree. C. above the Tg of the resin to form toner particles comprised of said polymeric resin, pigment and optionally a charge control agent;
- and
- (v) optionally separating and drying said toner.
Dependencies are inferred from the claim text.